Conductance Emulation Based Control for Series Stacked Energy Buffer

In single phase power conversion, an energy storage is required to supply the power mismatch between instantaneous ac power and dc power. The Series Stacked Energy Buffer (SSEB) is an active energy storage that requires a low value of capacitance to support the said power mismatch and ensure a ripple free voltage at dc port. The SSEB also incurs small power losses and occupies low volume. However, the existing control techniques for SSEB require dc-link current sensing and noise-prone differentiation function. To address these challenges, this paper proposes a conductance emulation control for SSEB circuit. The value of emulated conductance is changed to control the real power absorbed by the SSEB circuit. In result, the entire SSEB network becomes equivalent to a controlled frequency dependent conductance. This facilitates a straightforward analysis and intuitive understanding on the effect of SSEB topology on the operation of the system. This effect is further examined with a small signal model of SSEB circuit. The load transient and steady-state performance of the proposed controller are supported by simulation studies using MATLAB/Simulink.